Two-dimensional pattern formation in surfactant-mediated epitaxial growth

The effects of a surfactant on two-dimensional pattern formation in epitaxi al growth are explored theoretically using a simple model, in which an adat om becomes immobile only after overcoming a large energy barrier as it exch anges positions with a surfactant atom, and subsequent growth from such a s eed is further shielded. Within this model, a fractal-to-compact island sha pe transition can be induced by either decreasing the growth temperature or increasing the deposition flux. This and other intriguing findings are in excellent qualitative agreement with recent experiments.